Volcano

The volcano is a type of hazard in Heretic. Volcanoes are usually placed in the lava. They are first encountered in. Volcanoes are pretty rare: only two levels in registered Heretic contain them. The Shadow of the Serpent Riders expansion adds five more levels with volcanoes.

Mechanics
The volcano launches a random number (from one to three) of large fireballs (called in the code) into the air at random intervals. They then fall to the ground and explode, creating four small fireballs (called in the code) that also fly up and then fall down. Both the player and monsters can take damage by touching large or small fireballs. Touching a large fireball causes it to explode.

Appearance statistics
In the IWADs the volcano is first encountered on these maps per skill level:

The IWADs contain the following numbers of volcanos per skill level:

Trivia

 * is the only level in Heretic where skill level affects the placement of volcanoes. Of the five volcanoes in this level, two are marked to only spawn at medium and hard skill levels (things 224 and 314), and one is marked to only spawn at hard skill level (thing 315). It is unknown if this was intentional or if it was just a mistake. The latter assumption is also supported by the fact that two of these volcanoes have a deaf flag set (things 314 and 315).